An introduction to the Scottish mineral Geological Conservation Review sites

Abstract

Scotland for its small size possesses a more complex geology than anywhere else in the world, consequently the country has a rich mineral legacy. There are around 650 mineral species now known to occur in Scotland; most of these are silicates, but the assemblage also includes oxides, sulphides and sulphates. Most formed by igneous or metamorphic processes. The igneous minerals produced depends on the nature of the intrusion, be it granitoid or basic to ultrabasic, and also on when it formed in the intrusive cycle; i.e., in early magmatic stages or in late-stage veining. Metamorphic minerals are the product of temperature, pressure and the nature of the precursor rock. A few minerals, such as carbonates and iron oxides are of sedimentary origin, and some formed by the addition of material (mostly metal elements) to rocks, a process known as mineralisation. The choice of mineral GCR sites is based on the presence of rare species and/or unusually large concentrations of minerals and/or the provision of good evidence of geological processes. All sites have national significance and the Meall Tairneachan-Creag An Loch Ba–Zn–Pb deposit is of world-class importance. The coverage of the nation’s mineral species is demonstrated by providing a brief description of them which highlights the sites at which they occur. Thus it will be seen that some minerals are predominant at a number of sites: e.g., galena is the main ore mineral at Leadhills-Wanlockhead, Tyndrum and Strontian. Similarly silica, mostly in the form of quartz is present at many sites, but only in its more exotic form such as agate or cairngorm is it the raison d’etre for its choice as a GCR site.